https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98549
--- Comment #12 from Segher Boessenkool <segher at gcc dot gnu.org> --- for (long i; i != compress_n_blocks; ++i) "i" is uninitialized; accessing it is UB. So this is ice-on-invalid. I have no doubt there is an actual bug somewhere here. We just do not have valid code yet as testcase (preferably shorter than this, and C code, so that it is easier and can run on more systems).